1. Field of the Invention
This invention generally relates to recording and reproducing apparatus such as magnetooptical recording and reproducing apparatus using a magnetooptical head or the like. More particularly, the present invention relates to a magnetooptical head capable of reducing the diffraction limit of the spot diameter of the laser beam irradiated on a recording medium, and to a recording and reproducing apparatus capable of recording at a higher density by use of the magnetooptical head unit.
2. Description of the Related Art
Recently, as multimedia have become popular, a magnetooptical recording medium which is able to record and reproduce a large amount of data rapidly and at a higher density has attracted a great deal of public attention. For example, which regard to the recording on a magnetooptical recording medium capable of overwrite recording, a laser beam is irradiated on the magnetooptical recording medium, while a magnetic field corresponding to input information is applied to the positions on the medium at which the laser beam has been irradiated. When this magnetooptical recording medium is reproduced, a laser beam weaker than that at the time of recording is applied to the medium, and the polarizing angle of the reflected light from the medium, which has the polarizing angle of the reflected light depending on the recording magnetization direction, is detected so that the information can be reproduced.
As to the head mechanism used in this magnetooptical recording and reproducing apparatus, an optical head 2 and a magnetic head 3 as shown in FIG. 1 have been provided to oppose each other along their center line on both sides of a disk recording medium 1. In this case, since each of the optical head 2 and magnetic head 3 has a large shape and weight, the heads 2, 3 are supported by a support member 7, and moved along the sides of the disk recording medium 1 by the rotation of a screw rotating shaft 4 driven by a drive motor 6, so that the information can be recorded, reproduced or erased. This system has a drawback in that it has a large three-dimensional shape and a large weight. Thus it is not suitable for small-size, light weight, large-capacity, and high-speed access for recording, reproduction and erasion which the disk recording medium and recording and reproducing apparatus are requested to have. On the other hand, a magnetooptical head mechanism 20 as shown in FIG. 2 is known as the technology for combining the optical head 2 and magnetic head 3 into one unit, thereby reducing the size of the recording and reproducing apparatus. That is, a drive 13 for an object lens 10 of an optical head system 12 and a magnetic head/slider 14 in which a magnetic head coil 21 is provided are integrally combined. The magnetic head/slider 14 has an aperture 43 formed therethrough for focused light 32 of a laser beam 11 emitted from the optical head. The recording and reproducing apparatus using this kind of magnetooptical head is considerably small in its solid volume, but still not satisfactory enough to meet the small-size, light weight, large-capacity, and high-speed access for recording, reproduction and erasion which the disk recording medium and recording and reproducing apparatus of today are requested to have.
In addition, another system is known in which the head is secured to the tip of an arm with its fulcrum positioned around the disk recording medium. The arm is swung in parallel to the surface of the disk recording medium, thereby recording, reproducing or erasing information on or from the disk recording medium. The drive system for moving the optical head in parallel to the surface of the disk recording medium by a swing arm or linear motor is proposed in Japanese Patent Laid-open Gazette No. 5-54457. The system for driving an optical head by a swing arm is also proposed in Japanese Patent Laid-open Gazettes Nos. 8-7309 and 3-203848. Moreover, the construction having a laser beam reflecting surface formed on the magnetic head is disclosed in Japanese Patent Laid-open Gazette No. 3-280233. The problem with this system is that it is not able to achieve the suitable small size and light weight which the recording and reproducing apparatus of today is requested to have. The recording and reproducing drive capable of answering the remarkable demand for small size and high-density recording capability of a magnetooptical recording medium must be more compact, lighter in weight, and have higher-speed access for recording, reproduction and erasion. If the optical head and magnetooptical head are driven by the known swing arm system, the heads will hit the disk recording medium, causing head crash with the result that the head and disk recording medium are broken, or destroyed.